contributed largely to the noise component in the low-frequency band of ECG HRV signal. In an
examination of individual nights from all missions, the ECG HRV signal measured 51 nights >80%
in the low frequency range. In contrast, the CPC signal measured only 1 night >80% in the low-
frequency range. Correlation for the CPC signal was also much stronger to responses from the
subjective sleep diary questions than traditional ECG HRV. It was clear that that the CPC signal
was far more closely aligned with the subjective feedback of the crews across all environments
in regards to their sleep quality, patterns, and experiences. The data also strongly indicated that
CPC is a valuable and useful tool for monitoring sleep stability in extreme and operational
environments.
This investigation is complete; however additional results are pending publication.